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In the first large-scale human study of the chemical, some found with bisphenol A in their urine had more than double the normal risk of heart disease and diabetes.
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The first large-scale human study of a chemical widely used in plastic products, including baby bottles and tin can linings, found double the risk of cardiovascular disease, diabetes and liver problems in people with the highest concentrations in their urine, British researchers reported Tuesday.
The findings confirm earlier results obtained in animals, increasing pressure on the Food and Drug Administration to limit use of the chemical Bisphenol A, commonly called BPA.
The chemical is the primary ingredient of polycarbonate plastics, which are found in myriad modern products, such DVDs, drinking bottles and lenses of sunglasses.
There have been growing concerns about its safety as studies in rodents have linked it to diabetes, brain damage, developmental abnormalities, pre-cancerous changes in the prostate and breast and a variety of other health problems.
About 7 billion pounds of the chemical are produced worldwide each year and studies by the Centers for Disease Control and Prevention have found that 93% of Americans have detectable levels of the chemical in their urine.
The new findings are published in this week’s edition of the Journal of the American Medical Assn., but were released early to coincide with an FDA hearing on BPA in Washington.
“This is a human study that really calls into question FDA’s assertion that BPA is safe,” said Dr. Anila Jacob of the Environmental Working Group, an activist group.
An FDA representative, however, defended the agency’s actions at the Tuesday hearing. “A margin of safety exists that is adequate to protect consumers, including infants and children, at the current levels of exposure, said Laura Tarentino, a senior FDA scientist.
Many experts already think the writing is on the wall for the chemical, however.
A draft report issued earlier this year by the government’s National Toxicology Program, which has no regulatory authority, concluded that there was “some concern” that the chemical poses a risk to fetuses, babies and children.
Health Canda, Canada’s national public health department, also earlier this year released a report calling BPA “a potentially harmful chemical” – becoming the first regulatory body in the world to do so.
Baby bottle manufacturers are already looking for replacements for the chemical. And both Wal-Mart Stores Inc. and Toys R Us Inc. have announced their plans to shift away from products containing BPA.
BPA was first synthesized in 1891 and came into wide use in the 1940s and 1950s because of the toughness and durability of polycarbonates made from it.
But some BPA remains intact in the plastic and leaches out over time, particularly when it comes in contact with hot liquids.
The chemical industry and the FDA have long relied on two large animal studies which showed that high concentrations of the chemical fed to the rodents produced no serious adverse effects.
There have been no previous large studies of the chemical in humans because researchers considered it inappropriate to administer the chemical for tests.
Dr. David Melzer of the Peninsula Medical School in Exeter, Britain, and his colleagues took advantage of results from the 2003-2004 U.S. National Health and Nutrition Examination Survey, which for the first time measured concentrations of BPA in urine from a representative sample of 1,455 adults.
They found that the quarter of the population with the highest BPA levels – which were still at levels the FDA considers safe – were more than twice as likely to suffer from diabetes and cardiovascular disease as those in the quarter with the lowest levels.
The cause of the increased risk is unclear, but two studies reported earlier this year give hints. Spanish researchers reported in April that in mice, BPA causes pancreatic cells to increase their production of insulin, leading to the well-known metabolic syndrome that is a precursor of both diabetes and heart disease.
And an August study by endocrinologist Nira Ben-Jonathan of the University of Cincinnati showed that BPA, like estrogen, impairs the ability of human fat tissue to secrete adiponectin, which protects against heart attacks and diabetes.
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